Friction stir welding apparatus

ABSTRACT

In a friction stir welding apparatus that can control a penetrating position of a probe with respect to a processing target member to an optimum position at a time of friction stir welding by detecting a wear volume and a tip position of the probe, as a drive mechanism moves down a holder having a coefficient of thermal expansion larger than that of the probe and holding the probe, a detector can freely detect a length of a member including the holder and the probe, and a probe detection mechanism can freely detect a tip length, which is the length of the member of only the probe.

BACKGROUND OF THE INVENTION

The present invention relates to a friction stir welding apparatus, andmore particularly relates to a friction stir welding apparatus having aprobe detection mechanism, a processing-member detection mechanism, anda probe cleaning mechanism.

In recent years, there has been proposed a friction stir weldingapparatus that performs friction stirring on a predetermined weldingportion in a processing target component formed by a plurality of metalplates such as aluminum plates by a probe rotating at a high speed, inaddition to general arc welding, to weld the metal plates with eachother. Even in a strength component of a movable body such as anautomobile, a configuration having a welding portion welded by afriction stir welding apparatus has been realized.

In such a friction stir welding apparatus, the rotating probe and theprocessing target component need to be moved relative to each other toweld a predetermined welding portion accurately. Accordingly, it isimportant to execute friction stir welding by detecting parametersrequired therefor with high accuracy, taking the detection valuesthereof into consideration.

Under such circumstances, although it is not related to a friction stirwelding apparatus, Japanese Patent Application Laid-open Publication No.2002-283059 discloses setting of a shaft reference position of a servospot welding gun and a robot control apparatus therefor. The robotcontrol apparatus has such a configuration that a movable welding tip ofthe welding gun is pressed against a fixed welding tip until anestimated disturbance load reaches a set first threshold, and when theestimated disturbance load has reached the first threshold, the movablewelding tip is driven in a direction in which the both tips are awayfrom each other until the estimated disturbance load reaches a secondthreshold smaller than the first threshold, to set, update, and storethe shaft position of the movable welding tip when the second thresholdis reached as a reference position, thereby enabling to obtain andupdate the reference position in the same manner even when the weldingtip is worn off.

Japanese Patent Application Laid-open Publication No. 2007-30017 relatesto a friction stirring welding method and discloses a configuration inwhich after a rotation jig is moved to a temporary setting positiondetermined based on deflection amount data of a support table generatedwhen a welding pressure is applied and thickness data of an overlappedportion, position control of a servo motor is canceled at the temporarysetting position and torque of the servo motor is controlled. After acertain time has passed since the start of torque control, a movingdistance of the rotation jig is measured, to obtain a welding operationstart position based on the obtained moving distance and the temporarysetting position, and then a friction stir welding operation withrespect to the overlapped portion is performed by using the weldingoperation start position as a reference.

Japanese Patent Application Laid-open Publication No. H5-138361 relatesto a nozzle cleaning apparatus of a welding torch, although it is notrelated to a friction stir welding apparatus. The nozzle cleaningapparatus includes a pre-processing device 10 in which a plurality oflong wires 12 having a tip bent inward and a plurality of short wires 13having a tip formed in an outward hook shape are erected on acircumference slightly smaller than an opening end diameter of a nozzle7 of a fixed table 11, and a main processing device 20 in which aplurality of long brushing bars 22 and short brushing bars 23 havingfine wires implanted at the end thereof are erected on a circumferenceslightly smaller than the opening end diameter of the nozzle 7 of aturntable 21 and a cylindrical wire brush 24 is provided in a standingcondition outside thereof, thereby eliminating spatters near a gasoutlet 9 and circular spatters at the opening end of the nozzle 7.

SUMMARY OF THE INVENTION

According to the studies performed by the present inventors, JapanesePatent Application Laid-open Publication No. 2002-283059 discloses theconfiguration that enables to obtain and update the reference positionin the same manner even when the welding tip is worn off is disclosed.However, there is no disclosure as to how to obtain the size of theprobe to be used for friction stir welding.

According to the studies performed by the present inventors, JapanesePatent Application Laid-open Publication No. 2007-30017 discloses theconfiguration in which deflection amount data of the support table andthickness data of the overlapped portion are used to obtain the weldingoperation start position. However, a surface position itself of thesupport table and an upper position itself of each member constitutingthe overlapped portion are not detected, and thus it is considered thatthere is still a room for improvement in setting of a value to bedetected.

According to the studies performed by the present inventors, JapanesePatent Application Laid-open Publication No. H5-138361 discloses theconfiguration that enables nozzle cleaning of the welding torch.However, there is no disclosure as to how to execute the cleaning withrespect to the rotatable probe.

Therefore, under present circumstances, a friction stir weldingapparatus having a new configuration that can control a penetratingposition of a probe with respect to a processing target member to anoptimum position at the time of friction stir welding, by detecting awear volume and a tip position of the probe, the position of a mountingsurface of a mounting jig, and the position of a processing target sidesurface of the processing target member mounted on the mounting surfacehas been desired.

The present invention has been achieved in view of the above studies,and an object of the present invention is to provide a friction stirwelding apparatus that can control a penetrating position of a probewith respect to a processing target member to an optimum position at atime of friction stir welding, by detecting a wear volume and a tipposition of the probe, in an optimum mode for executing friction stirwelding.

To achieve the above object, a first aspect of the present invention isto provide a friction stir welding apparatus comprising: a mountingmember on which a processing target member is mounted; a welding toolhaving a probe, a holder having a coefficient of thermal expansionlarger than that of the probe and holding the probe detachably, a drivemechanism that can drive the holder holding the probe to freely move theprobe vertically with respect to a processing target side surface of theprocessing target member and can freely rotate with respect to theprocessing target member, and a detector that can freely detect a lengthof a member including the holder and the probe as the drive mechanismmoves the holder holding the probe downward; a movement mechanism havingan arm to which a fitting jig fitted with the welding tool is fixed soas to be able to freely move the welding tool with respect to theprocessing target member by moving the arm; and a probe detectionmechanism that can freely detect a tip length, which is a length of amember of only the probe, as the drive mechanism moves the holderholding the probe downward.

According to a second aspect of the present invention, in addition tothe first aspect, the probe detection mechanism has a block member whoseposition is fixed and a displacement sensor fixed to the block memberside, and at a time of detecting the tip length of the probe, after themovement mechanism moves the arm so that the welding tool faces theblock member, the drive mechanism moves down the holder holding theprobe to press an upper surface side of the block member by a tip of theprobe, and a contact member of the displacement sensor comes in contactwith an abutment member of the welding tool and is moved, therebydetecting displacement of the contact member.

According to a third aspect of the present invention, in addition to thesecond aspect, the detector can freely detect an amount of verticalmovement of the holder and the probe held by the holder by the drivemechanism, and detects the length of the member including the holder andthe probe based on the amount of movement after the movement mechanismmoves the arm so that the welding tool faces the block member until theholder holding the probe is moved down by the drive mechanism to pressthe upper surface side of the block member by the tip of the probe.

According to a fourth aspect of the present invention, in addition tothe second or third aspect, the friction stir welding apparatus furthercomprising a supplementary support mechanism that supports the mountingmember by a support member to supplementarily support only a verticalposition of the processing target member, wherein the supplementarysupport mechanism is fitted to the arm, and at a time of detecting thelength of the member including the holder and the probe and the tiplength of the probe, the welding tool is moved down so that the tip ofthe probe presses the upper surface side of the block member, and thesupport member supports the lower surface side of the block member.

According to a fifth aspect of the present invention, in addition to anyof the first to fourth aspects, the friction stir welding apparatusfurther comprising a probe cleaning mechanism that cleans the probe,wherein the probe cleaning mechanism has a roughing unit and a finalpolishing unit, and at a time of cleaning the probe, after the movementmechanism moves the arm so that the welding tool faces the roughingunit, the welding tool is moved down to accommodate the tip of the probein the roughing unit, and the welding tool is rotated to rough the tip,and after the movement mechanism moves the arm so that the welding toolfaces the final polishing unit, the welding tool is moved down toaccommodate the tip of the probe in the final polishing unit, and thewelding tool is rotated to polish the tip.

According to a sixth aspect of the present invention, in addition to anyof the first to fifth aspects, the detector can freely detect the amountof vertical movement of the holder and the probe held by the holder bythe drive mechanism, and detects the amount of movement after themovement mechanism moves the arm so that the welding tool faces amounting surface of the mounting member until the welding tool is moveddown to press the mounting surface of the mounting member by the tip ofthe probe.

According to a seventh aspect of the present invention, in addition tothe sixth aspect, the friction stir welding apparatus further comprisinga supplementary support mechanism that supports the mounting member by asupport member to supplementarily support only a vertical position ofthe processing target member, wherein at a time of detecting the amountof movement after the movement mechanism moves the arm so that thewelding tool faces the mounting surface of the mounting member until thewelding tool is moved down to press the mounting surface of the mountingmember by the tip of the probe, the welding tool is moved down to pressthe mounting surface of the mounting member by the tip of the probe andthe support member supports an opposite side to the mounting surface ofthe mounting member.

According to an eighth aspect of the present invention, in addition toany of the first to seventh aspects, the friction stir welding apparatusfurther comprising: a pressing member that can freely press theprocessing target member mounted on the mounting member; and aprocessing-member detection mechanism having a displacement sensor fixedto the mounting member side, wherein when the pressing member presses anupper surface of the processing target member, the contact member of thedisplacement sensor comes in contact with the pressing member side andis moved, thereby detecting an amount of displacement of the contactmember.

According to a ninth aspect of the present invention, in addition to theeighth aspect, the processing target member has a lower member and anupper member, and when the pressing member presses an upper surface ofthe lower member mounted on the mounting member, the contact member ofthe displacement sensor comes in contact with the pressing member sideand is moved, thereby detecting the amount of displacement of thecontact member, or when the pressing member presses an upper surface ofthe upper member mounted on the lower member, the contact member of thedisplacement sensor comes in contact with the pressing member side andis moved, thereby detecting the amount of displacement of the contactmember.

According to a tenth aspect of the present invention, in addition to anyof the first to ninth aspects, the probe detection mechanism, theprocessing-member detection mechanism, the probe cleaning mechanism, andthe processing target member mounted on the mounting member are arrangedwithin a movable range of the welding tool defined by the movement ofthe arm by the movement mechanism.

According to an eleventh aspect of the present invention, in addition toany of the first to tenth aspects, the movement mechanism is anindustrial robot.

According to the configuration of the first aspect of the presentinvention, as the drive mechanism moves down the holder having thecoefficient of thermal expansion larger than that of the probe andholding the probe, the detector can freely detect the length of themember including the holder and the probe, and the probe detectionmechanism can freely detect the tip length, which is the length of themember of only the probe. Accordingly, because the length of the memberincluding the holder and the probe reflects thermal expansion of theholder and wear of the probe, correction of an insertion amount of theprobe into the processing target member at the time of friction stirwelding to be performed by using the friction stir welding apparatus canbe performed in an appropriate manner. Furthermore, because the tiplength of the probe reflects only the wear of the probe, when the wearvolume of the probe exceeds an upper limit, the probe can beappropriately replaced by a new probe. Consequently, the penetratingposition of the probe with respect to the processing target member canbe controlled to an optimum position at the time of friction stirwelding, particularly by detecting the wear volume and the tip positionof the probe, in an optimum mode for executing friction stir welding.

According to the configuration of the second aspect of the presentinvention, the probe detection mechanism has the block member whoseposition is fixed and the displacement sensor fixed to the block memberside, and at the time of detecting the tip length of the probe, afterthe movement mechanism moves the arm so that the welding tool faces theblock member, the drive mechanism moves down the holder holding theprobe to press the upper surface side of the block member by the tip ofthe probe, and the contact member of the displacement sensor comes incontact with the abutment member of the welding tool and is moved,thereby detecting displacement of the contact member. Consequently, thewear volume and the tip position of the probe can be reliably detected,while reliably fixing the position of the probe at the time of executingdetection with a simple configuration.

According to the configuration of the third aspect of the presentinvention, the detector can freely detect the amount of verticalmovement of the holder and the probe held by the holder by the drivemechanism, and detects the length of the member including the holder andthe probe based on the amount of movement after the movement mechanismmoves the arm so that the welding tool faces the block member until theholder holding the probe is moved down by the drive mechanism to pressthe upper surface side of the block member by the tip of the probe.Consequently, the tip position of the probe can be reliably detectedwith a simple configuration.

According to the configuration of the fourth aspect of the presentinvention, the supplementary support mechanism that supports themounting member by the support member to supplementarily support onlythe vertical position of the processing target member is provided. Thesupplementary support mechanism is fitted to the arm, and at the time ofdetecting the length of the member including the holder and the probeand the tip length of the probe, the welding tool is moved down so thatthe tip of the probe presses the upper surface side of the block member,and the support member supports the lower surface side of the blockmember. Consequently, at the time of executing friction stir welding,the probe and the processing target member can be positioned moreaccurately, thereby enabling to perform friction stir welding whilereliably controlling the distance between the probe and the processingtarget member to a predetermined distance. Furthermore, the wear volumeand the tip position of the probe can be detected more reliably, whilefixing the position of the probe at the time of executing the detectionmore reliably.

According to the configuration of the fifth aspect of the presentinvention, the probe cleaning mechanism that cleans the probe is furtherprovided. The probe cleaning mechanism has the roughing unit and thefinal polishing unit, and at the time of cleaning the probe, after themovement mechanism moves the arm so that the welding tool faces theroughing unit, the welding tool is moved down to accommodate the tip ofthe probe in the roughing unit, and the welding tool is rotated to roughthe tip. Thereafter, after the movement mechanism moves the arm so thatthe welding tool faces the final polishing unit, the welding tool ismoved down to accommodate the tip of the probe in the final polishingunit, and the welding tool is rotated to polish the tip. Consequently,the probe can be cleaned reliably by using rotation of the probe with asimple configuration.

According to the configuration of the sixth aspect of the presentinvention, the detector can freely detect the amount of verticalmovement of the holder and the probe held by the holder by the drivemechanism, and detects the amount of movement after the movementmechanism moves the arm so that the welding tool faces the mountingsurface of the mounting member until the welding tool is moved down topress the mounting surface of the mounting member by the tip of theprobe. Consequently, the surface position of the mounting surface of themounting member can be reliably detected with a simple configuration,without providing any additional sensor for detecting the mountingsurface of the mounting member.

According to the configuration of the seventh aspect of the presentinvention, the supplementary support mechanism that supports themounting member by the support member to supplementarily support onlythe vertical position of the processing target member is provided. Atthe time of detecting the amount of movement after the movementmechanism moves the arm so that the welding tool faces the mountingsurface of the mounting member until the welding tool is moved down topress the mounting surface of the mounting member by the tip of theprobe, the welding tool is moved down to press the mounting surface ofthe mounting member by the tip of the probe and the support membersupports the opposite side to the mounting surface of the mountingmember. Consequently, at the time of executing friction stir welding,the probe and the processing target member can be positioned moreaccurately, thereby enabling to perform friction stir welding whilereliably controlling the distance between the probe and the processingtarget member to the predetermined distance. Furthermore, the surfaceposition of the mounting surface of the mounting member can be detectedmore reliably with a simple configuration, without providing anyadditional sensor for detecting the mounting surface of the mountingmember.

According to the configuration of the eighth aspect of the presentinvention, the pressing member that can freely press the processingtarget member mounted on the mounting member, and the processing-memberdetection mechanism having the displacement sensor fixed to the mountingmember side are further provided. When the pressing member presses theupper surface of the processing target member, the contact member of thedisplacement sensor comes in contact with the pressing member side andis moved, thereby detecting the amount of displacement of the contactmember. Consequently, a surface position of the processing target memberin the state of being mounted on the mounting member can be furtherdetected, and thus the penetrating position of the probe with respect tothe processing target member can be controlled reliably to the optimumposition at the time of friction stir welding.

According to the configuration of the ninth aspect of the presentinvention, the processing target member has the lower member and theupper member, and when the pressing member presses the upper surface ofthe lower member mounted on the mounting member, the contact member ofthe displacement sensor comes in contact with the pressing member sideand is moved, thereby detecting the amount of displacement of thecontact member, or when the pressing member presses the upper surface ofthe upper member mounted on the lower member, the contact member of thedisplacement sensor comes in contact with the pressing member side andis moved, thereby detecting the amount of displacement of the contactmember. Consequently, the upper surface position of each of theconstituent members of the processing target member in the state ofbeing mounted on the mounting member can be respectively detected, andthe penetrating position of the probe with respect to the processingtarget member can be controlled more reliably to the optimum position atthe time of friction stir welding.

According to the configuration of the tenth aspect of the presentinvention, the probe detection mechanism, the processing-memberdetection mechanism, the probe cleaning mechanism, and the processingtarget member mounted on the mounting member are arranged within amovable range of the welding tool defined by the movement of the arm bythe movement mechanism. Consequently, the overall configuration of thefriction stir welding apparatus can be maintained compact, and further,the wear volume and the tip position of the probe, the surface positionof the mounting surface of the mounting member, and the surface positionof the processing target member in the state of being mounted on themounting member can be detected, while necessarily cleaning the probe,in a mode with high positional consistency between the constituentelements.

According to the configuration of the eleventh aspect of the presentinvention, the movement mechanism is an industrial robot. Consequently,the probe can be moved accurately with respect to the probe detectionmechanism, the probe cleaning mechanism, and the processing targetmember mounted on the mounting member with a more general purposeconfiguration.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view showing an overall configuration of a frictionstir welding apparatus according to an embodiment of the presentinvention;

FIG. 2 is a schematic top view showing an arrangement range ofrespective constituent elements of the friction stir welding apparatusaccording to the embodiment;

FIG. 3 is a partial enlarged side view showing a probe detectionmechanism of the friction stir welding apparatus according to theembodiment;

FIG. 4 is a partial enlarged side view showing a processing-memberdetection mechanism of the friction stir welding apparatus according tothe present embodiment, showing a state where only a first member ismounted on a mounting jig;

FIG. 5 is a partial enlarged side view showing the processing-memberdetection mechanism of the friction stir welding apparatus according tothe present embodiment, showing a state where both the first member anda second member are mounted on the mounting jig;

FIG. 6 is a partial enlarged side view showing a state where a probe ofa welding tool of the friction stir welding apparatus according to theembodiment presses the mounting jig; and

FIG. 7 is a partial enlarged side view showing a probe cleaningmechanism of the friction stir welding apparatus according to theembodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A friction stir welding apparatus according to an embodiment of thepresent invention is explained in detail below with reference to theaccompanying drawings. In the drawings, an x-axis, a y-axis, and az-axis constitute a three-axis orthogonal coordinate system. A planedefined by the x-axis and the y-axis is parallel to a horizontal plane,and a normal direction of the z-axis is an upward direction.

A configuration of the friction stir welding apparatus according to thepresent embodiment is explained in detail with reference to FIGS. 1 to7.

FIG. 1 is a side view showing an overall configuration of the frictionstir welding apparatus according to the present embodiment. FIG. 2 is aschematic top view showing an arrangement range of respectiveconstituent elements of the friction stir welding apparatus according tothe present embodiment. FIG. 3 is a partial enlarged side view showing aprobe detection mechanism of the friction stir welding apparatusaccording to the present embodiment. FIG. 4 is a partial enlarged sideview showing a processing-member detection mechanism of the frictionstir welding apparatus according to the present embodiment, showing astate where only a first member is mounted on a mounting jig. FIG. 5 isa partial enlarged side view showing the processing-member detectionmechanism of the friction stir welding apparatus according to thepresent embodiment, showing a state where both the first member and asecond member are mounted on the mounting jig. FIG. 6 is a partialenlarged side view showing a state where a probe of a welding tool ofthe friction stir welding apparatus according to the present embodimentpresses the mounting jig. FIG. 7 is a partial enlarged side view showinga probe cleaning mechanism of the friction stir welding apparatusaccording to the present embodiment.

As shown in FIGS. 1 to 7, a friction stir welding apparatus 1 includes amounting table 10 fixedly installed on the floor F so that a processingtarget member W is mounted thereon, a processing-member detectionmechanism 20 fixedly installed on the mounting table 10, a welding tool30 that can be freely arranged opposite to the mounting table 10 abovethe mounting table 10, a supplementary support mechanism 40 that can befreely arranged so as to abut on a lower surface of the mounting table10 below the mounting table 10, a robot 50 fixedly installed on thefloor F so as to hold the welding tool 30 and the supplementary supportmechanism 40 by a fitting jig 52, a probe detection mechanism 60 fixedlyinstalled on the floor F, and a probe cleaning mechanism 80 fixedlyinstalled on the floor F.

Various constituent elements associated with the friction stir weldingapparatus 1 are appropriately controlled by receiving a control signaltransmitted from a controller C, to operate so as to perform frictionstir welding with respect to the processing target member W. Thecontroller C has an computing processing unit and a memory (both notshown) incorporated therein, and a control program for executingfriction stir welding, various pieces of data required therefor, anddata of a predetermined welding direction are stored in the memory.

As shown in FIG. 2, the processing target member W mounted on themounting table 10, the processing-member detection mechanism 20 arrangedso as to be able to freely advance and retract with respect to theprocessing target member W, the probe detection mechanism 60 fixedlyinstalled on the floor F, and the probe cleaning mechanism 80 fixedlyinstalled on the floor F are arranged in a movable range L indicating alimited range defined by the movement of an arm 54 of the robot 50 inwhich a probe 32 and an abutment member 36 of the welding tool 30 can belocated.

Specifically, the mounting table 10 includes a mounting jig 12 fixedlyinstalled on a mounting portion 10 a thereof so as to be able to freelymount the processing target member W thereon, and a holding member (notshown) arranged on the mounting jig 12 to detachably fix the processingtarget member W. The mounting jig 12 is a mounting member, and an uppersurface thereof is a mounting surface. The processing target member W istypically a plate member made of metal such as an aluminum material inwhich a first member W1 and a second member W2 are juxtaposed in avertical direction and respectively have an overlapped portion on eachother. Predetermined portions of the overlapped portions of the firstmember W1 and the second member W2 are welded along a predetermined weldline by the welding tool 30 that is moved along a predetermined weldingdirection. The position of the processing target member W on themounting jig 12 is maintained accurately by holding a part of theprocessing target member W by the holding member. As a drive source thatdrives the holding member, a motor or an air cylinder can be mentioned.Needless to mention, the holding member can be driven manually. Apressing member 22 a of the processing-member detection mechanism 20 canfunction also as the holding member.

A plurality of processing-member detection mechanisms 20 are typicallyprovided around the mounting jig 12. However, one processing-memberdetection mechanism 20 is explained for convenience sake of explanation.As shown in FIGS. 4 and 5, the processing-member detection mechanism 20includes the pressing member 22 a that can freely press the respectiveupper surfaces of the first member W1 and the second member W2 of theprocessing target member W mounted on the mounting jig 12, a motor 22 bfixed to a side of the mounting portion 10 a of the mounting table 10 toapply a drive force so that the pressing member 22 a can be freely movedbetween an upper position and a lower position, an abutment member 24fixedly installed on the pressing member 22 a, and a displacement sensor25 that can freely abut on the abutment member 24. As a drive sourcethat drives the pressing member 22 a, an air cylinder can be mentionedother than the motor.

The pressing member 22 a is typically a thick plate member made of metalsuch as an iron material having enough strength and rigidity. Thepressing member 22 a is pivotally supported by and fitted to a shaft 22c that connects the pressing member 22 a and the motor 22 b, and isfitted to a support member 22 e typically made of metal such as an ironmaterial having enough strength and rigidity. The motor 22 b is fixed toa lower surface of a base 22 d fixedly installed on the mounting portion10 a of the mounting table 10. The support member 22 e includes aturning shaft 22 f that pivotally supports the pressing member 22 a, anda turning shaft 22 g pivotally supported by a base 22 d, therebysupporting the pressing member 22 a freely movably between the upperposition and the lower position. A protection portion 22 h including apair of protection members 22 h 1 and 22 h 2 respectively protruding ona side where the abutment member 24 is provided (for example, when theabutment member 24 is provided on a negative direction side of a y-axisof the pressing member 22 a, a negative direction side of the y-axis) isprovided in the base 22 d.

Typically, the displacement sensor 25 is a contact-type displacementdetection sensor, and includes a sensor body 26 fixedly installed on thebase 22 d by a fixing member 26 a, a contact member 28 a connected tothe sensor body 26, and a bellows 28 b that covers the contact member 28a except the end thereof, into which the contact member 28 a isinserted. The contact member 28 a is applied with an urging force urgedupward with respect to the sensor body 26 by an urging member such as acoil spring (not shown) and is fitted to the sensor body 26. Thedisplacement sensor 25 detects an amount of displacement of the contactmember 28 a when the contact member 28 a is pushed into the sensor body26 against the urging force by the abutment member 24 and is moveddownward in a state with an upper end of the contact member 28 aabutting on a lower end of the abutment member 24, and transmits to thecontroller C a detection signal that enables detection of upper surfacepositions of the first member W1 and the second member W2 of theprocessing target member W when the pressing member 22 a is pressing theupper surfaces thereof with a predetermined load. At the time offriction stir welding, the upper surfaces thereof are surfaces on anentry side of the probe 32.

That is, in the processing-member detection mechanism 20, when the firstmember W1 and the second member W2 of the processing target member W aremounted on the mounting jig 12, or when only the second member W2 of theprocessing target member W is mounted on the mounting jig 12, the motor22 b is driven to move the shaft 22 c in the vertical direction.Accordingly, the pressing member 22 a turns around the rotation shafts22 f and 22 g defined in the support member 22 e, and correspondingthereto, the pressing member 22 a moves between the upper position shownin FIG. 1 and the lower position shown in FIGS. 4 and 5, and can freelyadvance and retract with respect to the first member W1 and the secondmember W2. When the pressing member 22 a is at the lower position shownin FIGS. 4 and 5 to press the upper surface of the first member W1 orthe second member W2 with a predetermined load, the lower end of theabutment member 24 abuts on the upper end of the contact member 28 a,and the contact member 28 a is moved downward while being pushed intothe sensor body 26 against the urging force. The displacement sensor 25detects an amount of displacement thereof, and transmits to thecontroller C a detection signal that enables detection of the uppersurface positions of the first member W1 and the second member W2 of theprocessing target member W.

To detect the upper surface positions of the first member W1 and thesecond member W2 of the processing target member W respectivelyaccording to the amount of displacement of the contact member 28 a byusing the displacement sensor 25, for example, the displacement sensor25 only needs to detect a difference between respective predeterminedreference positions of the first member W1 and the second member W2provided to the displacement sensor 25 and the position to which thecontact member 28 a is moved, and transmit a detection signal thereof tothe controller C. The controller C then calculates the respective uppersurface positions corresponding to the difference by referring to datasuch as a table format or a calculation formula stored in the memorythereof. At this time, the abutment member 24 follows a track thatpasses through between the pair of protection members 22 h 1 and 22 h 2,so as to be protected from unnecessary contact with other members by theprotection members 22 h 1 and 22 h 2. The pair of protection members 22h 1 and 22 h 2 can be configured such that when the track of theabutment member 24 deviates for any reason, the abutment member 24 abutson the corresponding member of the protection members 22 h 1 and 22 h 2and is guided therebetween.

The welding tool 30 includes a probe 32 that is typically a columnarmember made of metal such as heat-resistant alloy extending vertically,and is freely rotatable around a central axis Z, which is parallel to az-axis and freely movable in a vertical direction, a holder 34 that hasa coefficient of thermal expansion larger than that of the probe 32 anddetachably holds the probe 32, an abutment member 36 having a largediameter than that of the probe 32 and held by the holder 34 so as to befreely rotatable relative to the probe 32, and a drive mechanism 38 thatcauses the probe 32 held by the holder 34 to move vertically and rotatearound the central axis Z. The drive mechanism 38 includes a motor,which is a drive force source, and a shaft or the like that connects themotor and the holder 34 (both not shown) incorporated in a casing 38 a.The direction of the central axis Z of the probe 32 is a pressingdirection for pressing the processing target member W by rotating theprobe 32 at the time of friction stir welding. The abutment member 36 isfreely rotatable relative to the probe 32, but does not move relativelyin the vertical direction (the direction of the central axis Z of theprobe 32). Typically, the abutment member 36 includes a bearing member36 a fitted to the probe 32 and freely rotatable around the central axisZ, and a washer 36 b fixed to the lower portion of the bearing member 36a to prevent the bearing member 36 a from falling out. An upper end of acontact member 74 a of a displacement sensor 70 described later indetail can abut on a lower surface of the washer 36 b. At the time offriction stir welding using the friction stir welding apparatus 1, anamount of thermal expansion generated in the probe 32 is at a negligiblelevel such that it can be evaluated not to be generated substantially.

The casing 38 a also functions as a frame member fixed to the fittingjig 52 while supporting various constituent elements, and has a hollowcuboidal shape as an example of the structure thereof. In such a weldingtool 30, when the drive mechanism 38 moves the holder 34 holding theprobe 32 and the abutment member 36 downward, a lower part of the probe32 is press-fitted into the processing target member W, and can freelyreach a position at which the probe 32 penetrates the second member W2,passing through the first member W1 in the processing target member W.Particularly, as shown in FIGS. 3 and 6, the lower part of the probe 32can freely press an upper surface of a block member 68 of the probedetection mechanism 60 described later in detail and the upper surface(the mounting surface) of the mounting jig 12 with a predetermined loadrespectively. The predetermined load is set to a value smaller than aprocessing load at the time of performing friction stir welding withrespect to the processing target member W by using the probe 32. Themounting jig 12 is made of a metal material having hardness same as orhigher than that of the probe 32 of the welding tool 30. The uppersurface of the first member W1 of the processing target member W isreferred to as “processing target side surface Ws” for convenience sake.

A detector D typically including a rotary encoder is fixedly installedin the casing 38 a as a detector that detects an amount of verticalmovement of the probe 32 by the drive mechanism 38. The detector D canmeasure the number of rotations of the shaft or the like that connectsthe motor and the holder 34, to freely detect the moving distance of theholder 34 in the vertical direction, that is, an amount of verticalmovement of the probe 32 held by the holder 34 based on the number ofrotations.

Specifically, when the probe 32 held by the holder 34 is moved downwardfrom a predetermined reference position with respect to a side of theblock member 68 of the probe detection mechanism 60 by the drivemechanism 38 to press the upper surface of the block member 68 with apredetermined load by the lower end of the probe 32, the detector D canfreely detect a length of the member including the holder 34 and theprobe 32, typically, a length obtained by adding a length between anupper end and a lower end of the holder 34 and a length of the probe 32from the lower end of the holder 34 to the lower end of the probe 32,based on the amount of movement of the probe 32 and the holder 34holding the probe 32 that have moved down from the predeterminedreference position. When having detected the length of the memberincluding the holder 34 and the probe 32, the detector D transmits adetection signal thereof to the controller C. A thermally expandedlength of mainly the holder 34 due to heat generated at the time offriction stir welding and a worn-part length of the probe 32 at the timeof friction stir welding are reflected in the length of the memberincluding the holder 34 and the probe 32. The length of the memberbecomes long by the thermally expanded length of the holder 34, andbecomes short by the worn-part length of the probe 32. The lower end ofthe probe 32, that is, a surface at the tip end of the probe 32 is notlimited to a flat surface, and can be a curved surface or a surfacehaving irregularities, so long as the apical surface can press the blockmember 68 in a steady state.

When the probe 32 held by the holder 34 is moved downward from thepredetermined reference position by the drive mechanism 38 with respectto the upper surface of the mounting jig 12 to press the upper surfacethereof by the lower end of the probe 32 with the predetermined load,the detector D detects the amount of movement of the probe 32 and theholder 34 holding the probe 32 that have moved down from thepredetermined reference position, and transmits to the controller C adetection signal that enables detection of the upper surface position ofthe mounting jig 12. To detect the upper surface position of themounting jig 12 by using the detector D based on the amount of movementof the probe 32 and the holder 34 holding the probe 32, the controller Conly needs to calculate the upper surface position of the mounting jig12 corresponding to the amount of movement by referring to data such asthe table format or the calculation formula stored in the memory thereofbeforehand. The upper surface position of the mounting jig 12 can becalculated in the same manner by the detector D itself by using theamount of movement.

The supplementary support mechanism 40 includes a supplementary supportmember 42, which is typically a ball member made of metal such as aniron material, and abuts on a lower surface of the mounting portion 10 aon an opposite side to the mounting jig 12, and a holder 44 that holdsthe supplementary support member 42 rotatably, while maintaining thecentral position thereof immovable. In the supplementary supportmechanism 40, the supplementary support member 42 can freely support themounting table 10 supplementarily, while abutting on the lower surfaceof the mounting portion 10 a of the mounting table 10 at one point inthe upper portion of the supplementary support member 42, in a statewith the supplementary support member 42 facing the lower end of theprobe 32, putting the processing target member W therebetween.

The robot 50 is a movement mechanism that can freely move the weldingtool 30 and the processing target member W fixed on the mounting jig 12of the mounting table 10 relative to each other, and typically, is anindustrial robot. Specifically, the robot 50 includes a fitting jig 52made of metal in a two-pronged shape as viewed from the side, which istypically a chopped steel product and has an upper fitting portion 52 aand a lower fitting portion 52 b, respectively, fitted with the weldingtool 30 and the supplementary support mechanism 40 correspondingly, anarm 54 fitted with the fitting jig 52, which is typically a manipulatorhaving multiple joints, and a robot body 56 having a drive mechanismthat moves the arm 54, an computing processing unit, and a memoryincorporated therein (all not shown).

While the casing 38 a of the drive mechanism 38 of the welding tool 30is fitted and fixed to the upper fitting portion 52 a of the fitting jig52, the holder 44 of the supplementary support mechanism 40 is fittedand fixed to the lower fitting portion 52 b of the fitting jig 52. Aconnected portion between the upper fitting portion 52 a and the lowerfitting portion 52 b of the fitting jig 52 is fixed and fitted to asupport portion 54 a at one end of the arm 54 by fastening or the like,and the robot body 56 is connected to the other end of the arm 54. Byoperating the drive mechanism of the robot body 56, the arm 54 moves,and corresponding thereto, the welding tool 30 and the supplementarysupport mechanism 40 can be freely moved with multiple degrees offreedom to the left, right, up, and down, while maintaining the relativepositional relation between the welding tool 30 and the supplementarysupport mechanism 40.

Particularly as shown in FIG. 3, the probe detection mechanism 60includes a base 62 fixedly installed on the floor F, a support pillar 64provided in a standing condition to the base 62, a support 66 fixedlyinstalled on the support pillar 64, the block member 68 fixedlyinstalled to the support 66, and typically one displacement sensor 70fitted to the block member 68. The base 62, the support pillar 64, thesupport 66, and the block member 68 respectively have enough strengthand rigidity.

A corbel member 68 a made of a metal material having hardness same as orhigher than that of the probe 32 of the welding tool 30 is fixedlyinstalled on the upper surface of the block member 68. The lower end ofthe probe 32 can abut on and freely press the corbel member 68 a, andthe supplementary support member 42 of the supplementary supportmechanism 40 can abut on and freely press the lower surface of the blockmember 68.

Typically, the displacement sensor 70 is a contact-type displacementdetection sensor like the displacement sensor 25, and includes a sensorbody 72 fixedly installed to the block member 68 by a fixing member 72a, a contact member 74 a connected to the sensor body 72, and a bellows74 b that covers the contact member 74 a except the end thereof, intowhich the contact member 74 a is inserted. The contact member 74 a isapplied with an urging force urged upward with respect to the sensorbody 72 by an urging member such as a coil spring (not shown) and isfitted to the sensor body 72. The displacement sensors 70 can freelydetect a tip length of the probe 32 when the lower end of the probe 32abuts on the upper surface of the corbel member 68 a to press the corbelmember 68 a with the predetermined load and the supplementary supportmember 42 abuts on the lower surface of the block member 68 to press theblock member 68 with the predetermined load, according to the positionof the contact member 74 a when the contact member 74 a is pushed intothe sensor body 72 against the urging force by the abutment member 36and is moved downward, in a state with an upper end of the contactmember 74 a abutting on a lower surface of the abutment member 36, whichis typically the lower surface of the washer 36 b. The predeterminedload when the supplementary support member 42 abuts on the lower surfaceof the block member 68 and presses the block member 68 is a reactionforce of the predetermined load when the lower end of the probe 32presses the upper surface of the corbel member 68 a, and thepredetermined load is set to a value smaller than the processing load atthe time of performing friction stir welding with respect to theprocessing target member W by using the probe 32.

As shown in FIG. 3, in the probe detection mechanism 60, when the lowerend of the probe 32 abuts on and press the upper surface of the corbelmember 68 a with the predetermined load and the supplementary supportmember 42 abuts on and press the lower surface of the block member 68with the predetermined load, the lower surface of the abutment member 36abuts on the upper end of the contact member 74 a, and the contactmember 74 a is pushed into the sensor body 72 against the urging forceand is moved downward. Accordingly, the displacement sensors 70 canfreely detect a length from a predetermined reference surface of theprobe 32, that is, from the lower surface of the abutment member 36 tothe lower surface presenting a tip position of the probe 32, that is,the tip length of the probe 32 according to the moved distance of thecontact member 74 a. The reference surface of the probe 32 can bereplaced by a reference portion having other shapes such as a convex orconcave portion, so long as the upper end of the contact member 74 a canabut on the reference surface. As described above, the apical surface atthe end of the probe 32 is not limited to the flat surface, and can be acurved surface or a surface having irregularities. However, the tiplength of the probe 32 is a length from the lower surface of theabutment member 36 to a distal end of the curved surface or theirregularities.

When having detected the tip length of the probe 32, the detector Dtransmits a detection signal to the controller C. Because the probe 32does not thermally expand substantially due to heat generated at thetime of friction stir welding, only a wear volume of the probe 32 wornoff at the time of friction stir welding with respect to a new probe 32can be reflected in the tip length of the probe 32, and the tip lengthof the probe 32 becomes short by a worn-part length of the probe 32.That is, when the wear volume of the probe 32 exceeds a predeterminedlimit, the probe 32 needs to be replaced by a new probe 32.

Specifically, in the case of a new probe 32 to be used for the firsttime, because the probe 32 is not worn off, the tip length of the probe32 reflects a dimension error of the probe 32. When the probe 32 is analready used product, the probe 32 is worn off, and thus the tip lengthreflects the wear volume of the probe 32 in addition to the dimensionerror of the new probe 32. The wear volume of the probe 32 can beobtained by subtracting the tip length of the already used probe 32 fromthe tip length of a new probe 32 by the controller C. The controller Ccan use the tip length of the new probe 32 and the tip length of thealready used probe 32 that are respectively detected by the detector Dand stored in the memory. When the controller C determines that the wearvolume has exceeded the predetermined limit, it is desired that thecontroller C alerts an operator by lighting a display unit (not shown)or the like.

Particularly as shown in FIG. 7, the probe cleaning mechanism 80includes a support pillar 84 provided in a standing condition on thebase 62, a support 86 fixedly installed to the support pillar 84, and aroughing unit 88 a and a final polishing unit 88 b fixedly installed onthe support 86. The support pillar 84 and the support 86 respectivelyhave enough strength and rigidity. In a state with the probe 32 of thewelding tool 30 being rotated, at the time of accommodating the lowerpart of the probe 32 in the roughing unit 88 a, the roughing unit 88 acan scrape off processing chips adhered to the lower part of the probe32 by a cutting blade fixed in the roughing unit 88 a. Furthermore, whenthe lower part of the probe 32 abuts on the final polishing unit 88 b inthe state with the probe 32 of the welding tool 30 being rotated, thefinal polishing unit 88 b can polish the lower part of the probe 32having been roughed so that the probe 32 can be applied to friction stirwelding, by a finishing brush member fixed on the entire surface of thefinal polishing unit 88 b.

Particularly as shown in FIG. 7, the probe cleaning mechanism 80commonly uses the base 62 of the probe detection mechanism 60, and isprovided adjacent to the probe detection mechanism 60. Therefore, aftercleaning the used probe 32, the tip length of the probe 32 can beimmediately detected by fitting the cleaned probe 32 to the holder 34,and the length of the member including the holder 34 and the probe 32can be detected.

In this case, after the controller C moves the arm 54 via the robot body56 of the robot 50 and positions the welding tool 30 at an upperposition of the processing target member W mounted on the mounting jig12, the controller C moves the welding tool 30 downward to theprocessing target member W to press-fit the probe 32 into the processingtarget member W and rotate the probe 32, and stirs the processing targetmember W by the probe 32 while generating friction heat in theprocessing target member W. The controller C executes control to performfriction stir welding with respect to the processing target member Walong a predetermined weld line by moving the probe 32 and theprocessing target member W relative to each other by the arm 54 of therobot 50. The controller C respectively executes control to detect thetip length of the probe 32 by the probe detection mechanism 60, controlto detect the length of the member including the holder 34 and the probe32 by causing the probe 32 to press the upper surface of the blockmember 68 of the probe detection mechanism 60, control to detect theupper surface position of the mounting jig 12 by causing the probe 32 topress the upper surface thereof, control to detect the respective uppersurface positions of the first member W1 and the second member W2 of theprocessing target member W by the processing-member detection mechanism20, and control to clean the probe 32 by the probe cleaning mechanism80.

Next, various operations to be performed by the friction stir weldingapparatus 1 at the time of executing friction stir welding with respectto the processing target member W by using the friction stir weldingapparatus 1 having the configuration described above are explained belowin detail.

First, before starting a series of processes of friction stir welding,as preparation therefor, under control of the controller C, the drivemechanism of the robot body 56 appropriately moves the arm 54 verticallyand horizontally, to arrange the probe 32 of the welding tool 30 fittedto the upper fitting portion 52 a of the fitting jig 52 so as to facethe corbel member 68 a fixedly installed on the upper surface of theblock member 68 of the probe detection mechanism 60 above the corbelmember 68 a. At this time, the supplementary support member 42 of thesupplementary support mechanism 40 fitted to the lower fitting portion52 b of the fitting jig 52 is arranged to abut on the lower surface ofthe block member 68, putting the block member 68 therebetween.

When respective positions of the probe 32 and the supplementary supportmember 42 are realized in this manner, under control of the controllerC, as shown in FIG. 3, the drive mechanism 38 of the welding tool 30moves the holder 34 holding the probe 32 downward to move the probe 32downward, so that the lower end of the probe 32 abuts on the uppersurface of the corbel member 68 a to press the corbel member 68 a withthe predetermined load. At this time, one point in the upper portion ofthe supplementary support member 42 abuts on the lower surface of theblock member 68 to press the block member 68 with the predeterminedload.

At this time, the lower surface of the abutment member 36, that is, thelower surface of the washer 36 b abuts on the upper end of the contactmember 74 a, and the contact member 74 a of the displacement sensor 70is being moved downward while being pushed into the sensor body 72against the urging force. The displacement sensor 70 detects the lengthfrom the reference surface in the probe 32, that is, from the lowersurface of the abutment member 36 to the lower surface (the apicalsurface) of the lower end (the tip) of the probe 32, that is, the tiplength of the probe 32 according to the moved distance of the contactmember 74 a, which is the amount of displacement of the contact member74 a, and transmits the detection signal to the controller C. The tiplength of the probe 32 reflects a dimension error of the probe 32 whenthe probe 32 is new, and the tip length reflects the wear volume of theprobe 32 in addition to the dimension error in the new probe 32 when theprobe 32 is an already used product. In each case, the controller Cstores the detection value in the memory. The controller C reads thedetection value and performs computation of subtracting the tip lengthwhen the probe 32 is a used product from the tip length of a new probe32 to calculate the wear volume of the probe 32. When determining thatthe wear volume has exceeded the predetermined limit, the controller Clights the display unit. When the controller C lights the display unit,an operator replaces the probe 32 by a new one. However, when the probe32 to be used for friction stir welding this time is new, thecalculation process of the wear volume of the probe 32 is not performedas it is not required.

Simultaneously, at this time, the detector D detects the length of themember including the holder 34 and the probe 32, typically, a lengthobtained by adding the length from the lower end of the holder 34 to atleast a part of the upper part of the holder 34 and the length of theprobe 32 from the lower end of the holder 34 to the lower end of theprobe 32, based on the amount of movement of the probe 32 and the holder34 holding the probe 32 that have moved down from the predeterminedreference position, and transmits a detection signal to the controllerC. In the length of the member including the holder 34 and the probe 32,the thermally expanded length of mainly the holder 34 due to heatgenerated at the time of friction stir welding and the worn-part lengthof the probe 32 at the time of friction stir welding can be reflected.The length of the member becomes long by the thermally expanded lengthof the holder 34, and becomes short by the worn-part length of the probe32. The controller C stores the detection value in the memory in eachcase.

That is, when there is a time gap between the current friction stirwelding and the last friction stir welding and the temperature of theprobe 32 and the holder 34 decreases to a normal temperature, the lengthof the member including the holder 34 and the probe 32 becomes thereference length only including the dimension error when the probe 32 isnew, and becomes a length including the wear volume of the probe 32 inaddition to the dimension error when the probe 32 is a used product.Accordingly, in such cases, when the probe 32 is a used product, becausethe position of the lower end (the tip) of the probe 32 held by theholder 34 is deviated upward from the reference position of the newprobe by the wear volume, the position of the lower end of the probe 32held by the holder 34 needs to be corrected so as to be positioneddownward by the wear volume so that the lower end of the probe 32 ispositioned at the reference position. Accordingly, the controller Creads the detection value to calculate a correction amount to correctthe position of the lower end of the probe 32 so that the lower end ofthe probe 32 is positioned downward by the wear volume and is positionedat the reference position. However, when the probe 32 to be used for thecurrent friction stir welding is new, the calculation process of thecorrection amount of the position of the lower end of the probe 32 isnot performed as it is not required.

On the other hand, when there is no time gap between the currentfriction stir welding and the last friction stir welding and thetemperature of the probe 32 and the holder 34 is high, the length of themember including the holder 34 and the probe 32 becomes a referencelength including the amount of thermal expansion of the holder 34 andthe like except the probe 32 in addition to the dimension error of theprobe 32 when the probe 32 is new. When the probe 32 is a used product,the length of the member becomes a length including the amount ofthermal expansion of the holder 34 and the like except the probe 32 andthe wear volume of the probe 32 in addition to the dimension errorthereof. Accordingly, in each case, when the probe 32 is a used product,the position of the lower end (the tip) of the probe 32 held by theholder 34 is deviated from an initial position of the new probe by thewear volume of the probe 32 and the amount of thermal expansion of theholder 34 and the like except the probe 32. Therefore, the position ofthe lower end of the probe 32 held by the holder 34 needs to becorrected to balance out the amount of deviation thereof and positionedat the reference position. Accordingly, the controller C reads thedetection value to calculate a correction amount for balancing out thedeviated amount and positioning the lower end of the probe 32 at thereference position. However, even if the probe 32 to be used for thecurrent friction stir welding is new, when there is no time gap betweenthe current friction stir welding and the last friction stir welding andthe temperature of the probe 32 and the holder 34 is high, thecalculation process of the correction amount of the position of thelower end of the probe 32 is required and thus the calculation processis performed.

Next, under control of the controller C, the drive mechanism of therobot body 56 appropriately moves the arm 54 vertically andhorizontally, to arrange the probe 32 of the welding tool 30 fitted tothe upper fitting portion 52 a of the fitting jig 52 so as to face themounting jig 12 at the predetermined position above the mounting jig 12.At this time, the supplementary support member 42 of the supplementarysupport mechanism 40 fitted to the lower fitting portion 52 b of thefitting jig 52 is arranged to abut on the lower surface of the mountingportion 10 a, putting the mounting portion 10 a of the mounting table 10and the mounting jig 12 fitted to the mounting portion 10 a between theprobe 32 and the supplementary support member 42.

When respective positions of the probe 32 and the supplementary supportmember 42 are realized in this manner, under control of the controllerC, as shown in FIG. 6, the drive mechanism 38 of the welding tool 30moves the holder 34 holding the probe 32 downward to move the probe 32downward, so that the lower end of the probe 32 abuts on the uppersurface of the mounting jig 12 and presses the mounting jig 12 with thepredetermined load. At this time, one point in the upper portion of thesupplementary support member 42 abuts on the lower surface of themounting portion 10 a and presses the lower surface of the mountingportion 10 a with the predetermined load.

When the lower end of the probe 32 presses the upper surface of themounting jig 12 with the predetermined load, because the drive mechanism38 is moving the holder 34 downward, the probe 32 is also being moveddownward, and the detector D detects the amount of movement of the probe32 and the holder 34 holding the probe 32 that have moved down from thepredetermined reference position, and transmits the detection signal tothe controller C. The controller C calculates the upper surface positionof the mounting jig 12 corresponding to the amount of movement indicatedby the detection signal by referring to the data stored in the memorybeforehand. The upper surface position of the mounting jig 12 reflects adimension error and an installation error of the mounting jig 12 whenthe mounting jig 12 is new and newly used, or also reflects the level ofadherence of the paint of the processing target member W when themounting jig 12 is a used product. Therefore, when the error of theupper surface position of the mounting jig 12 or adherence of the paintthereto is larger than a reference, the controller C newly calculates acorrection amount of the position of the lower end of the probe 32 byadding the upper surface position of the mounting jig 12 to thecorrection amount of the position of the lower end of the probe 32.

Next, after only the second member W2 of the processing target member Wis mounted on the mounting jig 12, under control of the controller C, asshown in FIG. 4, the motor 22 b of the processing-member detectionmechanism 20 is driven to move the pressing member 22 a downward whilecausing the pressing member 22 a to enter into an area above the secondmember W2, and the lower surface of the pressing member 22 a is made toabut on the upper surface of the second member W2 and press the secondmember W2 with the predetermined load.

At this time, the lower end of the abutment member 24 abuts on the upperend of the contact member 28 a, and the contact member 28 a is beingmoved downward while being pushed into the sensor body 26 against theurging force. Accordingly, the moved distance of the contact member 28a, specifically, the amount of displacement of the contact member 28 a,which is a difference between a predetermined reference position of theupper surface position of the second member W2 and the position to whichthe contact member 28 a has been moved, is detected and a detectionsignal thereof is transmitted to the controller C. The controller Ccalculates the upper position of the second member W2 corresponding tothe amount of displacement of the contact member 28 a indicated by thedetection signal by referring to the data such as the table format orthe calculation formula stored in the memory beforehand. Because theupper surface position of the second member W2 reflects the platethickness and the installation error of the second member W2, when theerror of the upper surface position of the second member W2 is largerthan a reference, the controller C newly calculates the correctionamount of the position of the lower end of the probe 32 by adding theupper surface position of the second member W2 to the correction amountof the position of the lower end of the probe 32.

Next, under control of the controller C, the motor 22 b is driven tomove the pressing member 22 a upward to exit from the area above thesecond member W2. After the first member W1 is mounted on the secondmember W2 of the processing target member W mounted on the mounting jig12 of the mounting table 10, under control of the controller C, as shownin FIG. 5, the motor 22 b is driven to move the pressing member 22 adownward while causing the pressing member 22 a to enter into the areaabove the first member W1, and the lower surface of the pressing member22 a is made to abut on the upper surface of the first member W1 andpress the first member W1 with the predetermined load.

At this time, the lower end of the abutment member 24 abuts on the upperend of the contact member 28 a, and the contact member 28 a is beingmoved downward while being pushed into the sensor body 26 against theurging force. Accordingly, the moved distance of the contact member 28a, specifically, the amount of displacement of the contact member 28 a,which is a difference between a predetermined reference position of theupper surface position of the first member W1 and the position to whichthe contact member 28 a has been moved, is detected and a detectionsignal thereof is transmitted to the controller C. The controller Ccalculates the upper position of the first member W1 corresponding tothe amount of displacement of the contact member 28 a indicated by thedetection signal by referring to the data such as the table format orthe calculation formula stored in the memory beforehand. Because theupper surface position of the first member W1 reflects the platethickness and the installation error of the first member W1 in additionto those of the second member W2, when the error of the upper surfaceposition of the first member W1 is larger than a reference, thecontroller C newly calculates the correction amount of the position ofthe lower end of the probe 32 by adding the upper surface position ofthe first member W1 to the correction amount of the position of thelower end of the probe 32.

Next, under control of the controller C, as shown in FIG. 1, the drivemechanism of the robot body 56 appropriately moves the arm 54 verticallyand horizontally, to arrange the probe 32 of the welding tool 30 fittedto the upper fitting portion 52 a of the fitting jig 52 so as to facethe processing target member W at a predetermined position above theprocessing target member W, and cause the supplementary support member42 of the supplementary support mechanism 40 fitted to the lower fittingportion 52 b of the fitting jig 52 to abut on the lower surface of themounting portion 10 a of the mounting table 10 at one point in the upperpart of the supplementary support member 42 so as to face the lower partof the probe 32, putting the processing target member W therebetween. Atthis time, the position of the processing target member W is accuratelymaintained by holding a part of the processing target member W by theholding member.

Next, when respective positions of the probe 32 and the supplementarysupport member 42 are realized in this manner, under control of thecontroller C, the drive mechanism 38 of the welding tool 30 moves theholder 34 holding the probe 32 downward to move the probe 32 downward,so that the lower part of the probe 32 reaches a predetermined positionat which the lower part of the probe 32 passes through the first memberW1 of the processing target member W and penetrates the second memberW2. At this time, a penetration depth of the probe 32 passing throughthe first member W1 and penetrating the second member W2 is set by thecontroller C by correcting a standard penetration depth set beforehandby increasing/decreasing the penetration depth by the correction amountcalculated, taking into consideration the tip length of the probe 32,the upper surface position of the mounting jig 12, the upper surfaceposition of the second member W2, and the upper surface position of thefirst member W1 detected in the processes described above, and ismaintained substantially constant at the time of executing friction stirwelding. At this time, the drive mechanism 38 of the welding tool 30 canrotate the probe 32 via the holder 34 according to need.

Next, when the lower part of the probe 32 has reached the predeterminedposition in this manner, in a state where the drive mechanism 38 of thewelding tool 30 is continuously rotating the probe 32 under control ofthe controller C, the drive mechanism of the robot body 56 moves the arm54 so that the probe 32 and the supplementary support member 42 aremoved in a moving direction, which is the predetermined weldingdirection, in a state with their positional correspondence relation withrespect to the processing target members W being maintained. As aresult, the first member W1 and the second member W2 are friction stirwelded corresponding to a moved track of the lower part of the probe 32.Simultaneously, the supplementary support member 42 is being moved inthe predetermined welding direction while rotating in the holder 44, inthe state where the supplementary support member 42 abuts on the lowersurface of the mounting portion 10 a of the mounting table 10 at onepoint in the upper part of the supplementary support member 42, so as toface the lower part of the probe 32, putting the processing targetmember W therebetween.

Next, when the probe 32 has been moved in this manner to a predeterminedposition, which is an end point of a portion required to be frictionstir welded, with the movement of the arm 54, the drive mechanism 38 ofthe welding tool 30 moves the probe 32 upward, while maintaining therotation of the probe 32, to pull out the probe 32 from the processingtarget member W under control of the controller C, and after havinguplifted the probe 32 to the upper position thereof, stops the movementof the probe 32. The drive mechanism of the robot body 56 then moves thearm 54 so that the probe 32 and the supplementary support member 42 exitfrom the areas above and below the processing target member W, and stopsthe movement of the arm 54.

Next, when the probe 32 and the supplementary support member 42 haveexited in this manner, under control of the controller C, the motor 22 bis driven to move the pressing member 22 a upward so that the pressingmember 22 a exits from the area above the first member W of theprocessing target member W, and then stops the movement of the pressingmember 22 a.

Next, when the processing target member W is released by detaching theholding member and is dismounted from the mounting table 10, a processedproduct in which a predetermined portion is friction stir welded can beobtained.

Thereafter, when a next series of processes of friction stir welding isto be started without replacing the probe 32, before the tip length ofthe probe 32 is detected by using the probe detection mechanism 60, theprobe 32 is cleaned. When the probe 32 is replaced every time frictionstir welding is performed, such a process is not required.

Specifically, under control of the controller C, the drive mechanism ofthe robot body 56 appropriately moves the arm 54 vertically andhorizontally, to arrange the probe 32 of the welding tool 30 fitted tothe upper fitting portion 52 a of the fitting jig 52 so as to face theroughing unit 88 a of the probe cleaning mechanism 80 above the roughingunit 88 a. At this time, the supplementary support member 42 of thesupplementary support mechanism 40 fitted to the lower fitting portion52 b of the fitting jig 52 does not need to abut on the lower surface ofthe support 86.

When respective positions of the probe 32 and the supplementary supportmember 42 are realized in this manner, under control of the controllerC, as shown in FIG. 7, the drive mechanism 38 of the welding tool 30moves the holder 34 holding the probe 32 downward to move the probe 32downward while rotating the probe 32, so that the lower part of theprobe 32 is accommodated in the roughing unit 88 a and roughed for apredetermined time.

Next, when the predetermined time has passed, under control of thecontroller C, the drive mechanism 38 of the welding tool 30 moves theholder 34 holding the probe 32 upward to pull the probe 32 out from theroughing unit 88 a, and the drive mechanism of the robot body 56appropriately moves the arm 54 vertically and horizontally, to arrangethe probe 32 of the welding tool 30 fitted to the upper fitting portion52 a of the fitting jig 52 so as to face the final polishing unit 88 bof the probe cleaning mechanism 80 above the final polishing unit 88 b.At this time, the supplementary support member 42 of the supplementarysupport mechanism 40 fitted to the lower fitting portion 52 b of thefitting jig 52 does not need to abut on the lower surface of the support86.

When respective positions of the probe 32 and the supplementary supportmember 42 are realized in this manner, under control of the controllerC, the drive mechanism 38 of the welding tool 30 moves the holder 34holding the probe 32 downward to move the probe 32 downward whilerotating the probe 32, so that the lower part of the probe 32 isaccommodated in the final polishing unit 88 b and is subjected to finalpolishing for a predetermined time.

Thereafter, when the predetermined time has passed, the tip length ofthe probe 32 is sequentially detected by using the probe detectionmechanism 60, and the length of the member including the holder 34 andthe probe 32 is detected by causing the probe 32 to press the uppersurface side of the block member 68 of the probe detection mechanism 60.The upper surface position of the mounting jig 12 is detected by causingthe probe 32 to press the upper surface thereof, and after therespective upper surface positions of the first member W1 and the secondmember W2 of the processing target member W are detected by using theprocessing-member detection mechanism 20, friction stir welding can beexecuted.

According to the configuration of the present embodiment describedabove, when adherence or the like of the paint to the mounting jig 12can be ignored, the frequency of the process of detecting the uppersurface position of the mounting jig 12 by causing the probe 32 to pressthe upper surface thereof can be reduced, or the process can be omittedfor simplifying the process.

In the configuration of the present embodiment described above, aconfiguration example of applying the supplementary support mechanism 40has been explained. However, the supplementary support mechanism 40 canbe omitted when required processing accuracy is relatively low.

In the configuration of the present embodiment described above, it hasbeen explained that the supplementary support member 42 of thesupplementary support mechanism 40 is a ball member. However, othermovable members such as a rotatable member can be applied, or a fixedmember can be used when friction or the like hardly occurs.

According to the configuration of the present embodiment, as the drivemechanism 38 moves downward the holder 34 having a coefficient ofthermal expansion larger than that of the probe 32 and holding the probe32, the detector D can freely detect the length of the member includingthe holder 34 and the probe 32, and the probe detection mechanism 60 canfreely detect the tip length, which is the length of the member of onlythe probe 32. Accordingly, because the length of the member includingthe holder 34 and the probe 32 reflects thermal expansion of the holder34 and wear of the probe 32, an insertion amount of the probe 32 intothe processing target member W at the time of friction stir welding tobe performed by using the friction stir welding apparatus 1 can becorrected in an appropriate manner. Furthermore, because the tip lengthof the probe 32 reflects only the wear of the probe 32, when the wearvolume of the probe 32 exceeds the upper limit, the probe can beappropriately replaced by a new probe. Consequently, the penetratingposition of the probe with respect to the processing target member W canbe controlled to the optimum position at the time of friction stirwelding, by detecting the wear volume and the tip position of the probe32, in the optimum mode for executing friction stir welding.

According to the configuration of the present embodiment, the probedetection mechanism 60 has the block member 68 whose position is fixedand the displacement sensor 70 fixed to the side of the block member 68,and at the time of detecting the tip length of the probe 32, after themovement mechanism 50 moves the arm 54 so that the welding tool 30 facesthe block member 68, the drive mechanism 38 moves down the holder 34holding the probe 32 to press the upper surface side of the block member68 by the tip of the probe 32, and the contact member 74 a of thedisplacement sensor 70 comes in contact with the abutment member 36 ofthe welding tool 30 and is moved, thereby detecting displacement of thecontact member 74 a. Consequently, the wear volume and the tip positionof the probe 32 can be reliably detected, while reliably fixing theposition of the probe 32 at the time of executing detection with asimple configuration.

According to the configuration of the present embodiment, further, thedetector D can freely detect the amount of vertical movement of theholder 34 and the probe 32 held by the holder 34 by the drive mechanism38, and detects the length of the member including the holder 34 and theprobe 32 based on the amount of movement after the movement mechanism 50moves the arm 54 so that the welding tool 30 faces the block member 68until the holder 34 holding the probe 32 is moved down by the drivemechanism 38 to press the upper surface side of the block member 68 bythe tip of the probe 32. Consequently, the tip position of the probe 32can be reliably detected with a simple configuration.

Furthermore, according to the configuration of the present embodiment,the supplementary support mechanism 40 that supports the mounting member12 by the support member 42 to supplementarily support only the verticalposition of the processing target member W is provided. Thesupplementary support mechanism 40 is fitted to the arm 54, and at thetime of detecting the length of the member including the holder 34 andthe probe 32 and the tip length of the probe 32, the welding tool 30 ismoved down so that the tip of the probe 32 presses the upper surfaceside of the block member 68, and the support member 42 supports thelower surface side of the block member 68. Accordingly, at the time ofexecuting friction stir welding, the probe 32 and the processing targetmember W can be positioned more accurately, thereby enabling to performfriction stir welding while reliably controlling the distance betweenthe probe 32 and the processing target member W to the predetermineddistance. Furthermore, the wear volume and the tip position of the probe32 can be detected more reliably, while fixing the position of the probe32 at the time of executing the detection more reliably.

Further, according to the configuration of the present embodiment, theprobe cleaning mechanism 80 that cleans the probe 32 is furtherprovided. The probe cleaning mechanism 80 has the roughing unit 88 a andthe final polishing unit 88 b, and at the time of cleaning the probe 32,after the movement mechanism 50 moves the arm 54 so that the weldingtool 30 faces the roughing unit 88 a, the welding tool 30 is moved downto accommodate the tip of the probe 32 in the roughing unit 88 a, andthe welding tool 30 is rotated to rough the tip. Thereafter, after themovement mechanism 50 moves the arm 54 so that the welding tool 30 facesthe final polishing unit 88 b, the welding tool 30 is moved down toaccommodate the tip of the probe 32 in the final polishing unit 88 b,and the welding tool 30 is rotated to polish the tip. Consequently, theprobe 32 can be cleaned reliably by using rotation of the probe 32 witha simple configuration.

According to the configuration of the present embodiment, the detector Dcan freely detect the amount of vertical movement of the holder 34 andthe probe 32 held by the holder 34 by the drive mechanism 38, anddetects the amount of movement after the movement mechanism 50 moves thearm 54 so that the welding tool 30 faces the mounting surface of themounting member 12 until the welding tool 30 is moved down to press themounting surface of the mounting member 12 by the tip of the probe 32.Consequently, the surface position of the mounting surface of themounting member 12 can be reliably detected with a simple configuration,without providing any additional sensor for detecting the mountingsurface of the mounting member 12.

Furthermore, according to the configuration of the present embodiment,the supplementary support mechanism 40 that supports the mounting member12 by the support member 42 to supplementarily support only the verticalposition of the processing target member W is provided. At the time ofdetecting the amount of movement after the movement mechanism 50 movesthe arm 54 so that the welding tool 30 faces the mounting surface of themounting member 12 until the welding tool 30 is moved down to press themounting surface of the mounting member 12 by the tip of the probe 32,the welding tool 30 is moved down to press the mounting surface of themounting member 12 by the tip of the probe 32 and the support member 42supports the opposite side to the mounting surface of the mountingmember 12. Consequently, at the time of executing friction stir welding,the probe 32 and the processing target member W can be positioned moreaccurately, thereby enabling to perform friction stir welding whilereliably controlling the distance between the probe 32 and theprocessing target member W to the predetermined distance. Furthermore,the surface position of the mounting surface of the mounting member 12can be detected more reliably with a simple configuration, withoutproviding any additional sensor for detecting the mounting surface ofthe mounting member 12.

Further, according to the configuration of the present embodiment, thepressing member 22 a that can freely press the processing target memberW mounted on the mounting member 12, and the processing-member detectionmechanism 20 having the displacement sensor 25 fixed to the side of themounting member 12 are provided. When the pressing member 22 a pressesthe upper surface of the processing target member W, the contact member28 a of the displacement sensor 25 comes in contact with the side of thepressing member 22 a and is moved, thereby detecting the amount ofdisplacement of the contact member 28 a. Consequently, the surfaceposition of the processing target member W in the state of being mountedon the mounting member 12 can be further detected, and thus thepenetrating position of the probe 32 with respect to the processingtarget member W can be controlled reliably to the optimum position atthe time of friction stir welding.

According to the configuration of the present embodiment, the processingtarget member W has the lower member W2 and the upper member W1, andwhen the pressing member 22 a presses the upper surface of the lowermember W2 mounted on the mounting member 12, the contact member 28 a ofthe displacement sensor 25 comes in contact with the side of thepressing member 22 a and is moved, thereby detecting the amount ofdisplacement of the contact member 28 a, or when the pressing member 22a presses the upper surface of the upper member W1 mounted on the lowermember W2, the contact member 28 a of the displacement sensor 25 comesin contact with the side of the pressing member 22 a and is moved,thereby detecting the amount of displacement of the contact member 28 a.Consequently, the upper surface position of each of the constituentmembers W1 and W2 of the processing target member W in the state ofbeing mounted on the mounting member 12 can be respectively detected,and the penetrating position of the probe 32 with respect to theprocessing target member W can be controlled more reliably to theoptimum position at the time of friction stir welding.

According to the configuration of the present embodiment, the probedetection mechanism 60, the processing-member detection mechanism 20,the probe cleaning mechanism 80, and the processing target member Wmounted on the mounting member 12 are arranged within the movable rangeof the welding tool 30 defined by the movement of the arm 54 by themovement mechanism 50. Consequently, the overall configuration of thefriction stir welding apparatus 1 can be maintained compact, andfurther, the wear volume and the tip position of the probe 32, thesurface position of the mounting surface of the mounting member 12, andthe surface position of the processing target member W in the state ofbeing mounted on the mounting member 12 can be detected, whilenecessarily cleaning the probe 32, in the mode with high positionalconsistency between the constituent elements.

According to the configuration of the present embodiment, the movementmechanism 50 is an industrial robot. Accordingly, the probe 32 can bemoved accurately with respect to the probe detection mechanism 60, theprobe cleaning mechanism 80, and the processing target member W mountedon the mounting member 12 with a more general purpose configuration.

In the present invention, the shape, the arrangement, the number, andthe like of the members are not limited to those in the embodimentsexplained above, and it is needless to mention that the constituentelements can be modified as appropriate without departing from the scopeof the invention, such as appropriately replacing these elements byother ones having identical operational effects.

As described above, the present invention can provide a friction stirwelding apparatus that can control the penetrating position of the probewith respect to the processing target member to an optimum position atthe time of friction stir welding, by detecting a wear volume and a tipposition of the probe, in the optimum mode for executing friction stirwelding. Therefore, because of its general purposes and universalcharacteristics, applications of the present invention can be expectedin a wide range in the field of friction stir welding of a strengthmember of a movable body such as an automobile.

What is claimed is:
 1. A friction stir welding apparatus comprising: amounting member on which a processing target member is mounted; awelding tool having a probe, a holder having a coefficient of thermalexpansion larger than that of the probe and holding the probedetachably, a drive mechanism that can drive the holder holding theprobe to freely move the probe vertically with respect to a processingtarget side surface of the processing target member and can freelyrotate with respect to the processing target member, and a detector thatcan freely detect a length of a member including the holder and theprobe as the drive mechanism moves the holder holding the probedownward; a movement mechanism having an arm to which a fitting jigfitted with the welding tool is fixed so as to be able to freely movethe welding tool with respect to the processing target member by movingthe arm; and a probe detection mechanism that can freely detect a tiplength, which is a length of a member of only the probe, as the drivemechanism moves the holder holding the probe downward, wherein the probedetection mechanism has a block member whose position is fixed and adisplacement sensor fixed to the block member side, and at a time ofdetecting the tip length of the probe, after the movement mechanismmoves the arm so that the welding tool faces the block member, the drivemechanism moves down the holder holding the probe to press an uppersurface side of the block member by a tip of the probe, and a contactmember of the displacement sensor comes in contact with an abutmentmember of the welding tool and is moved, thereby detecting displacementof the contact member.
 2. The friction stir welding apparatus accordingto claim 1, wherein the detector can freely detect an amount of verticalmovement of the holder and the probe held by the holder by the drivemechanism, and detects the length of the member including the holder andthe probe based on the amount of movement after the movement mechanismmoves the arm so that the welding tool faces the block member until theholder holding the probe is moved down by the drive mechanism to pressthe upper surface side of the block member by the tip of the probe. 3.The friction stir welding apparatus according to claim 1, furthercomprising a supplementary support mechanism that supports the mountingmember by a support member to supplementarily support only a verticalposition of the processing target member, wherein the supplementarysupport mechanism is fitted to the arm, and at a time of detecting thelength of the member including the holder and the probe and the tiplength of the probe, the welding tool is moved down so that the tip ofthe probe presses the upper surface side of the block member, and thesupport member supports the lower surface side of the block member. 4.The friction stir welding apparatus according to claim 1, furthercomprising a probe cleaning mechanism that cleans the probe, wherein theprobe cleaning mechanism has a roughing unit and a final polishing unit,and at a time of cleaning the probe, after the movement mechanism movesthe arm so that the welding tool faces the roughing unit, the weldingtool is moved down to accommodate the tip of the probe in the roughingunit, and the welding tool is rotated to rough the tip, and after themovement mechanism moves the arm so that the welding tool faces thefinal polishing unit, the welding tool is moved down to accommodate thetip of the probe in the final polishing unit, and the welding tool isrotated to polish the tip.
 5. A friction stir welding apparatuscomprising: a mounting member on which a processing target member ismounted; a welding tool having a probe, a holder having a coefficient ofthermal expansion larger than that of the probe and holding the probedetachably, a drive mechanism that can drive the holder holding theprobe to freely move the probe vertically with respect to a processingtarget side surface of the processing target member and can freelyrotate with respect to the processing target member, and a detector thatcan freely detect a length of a member including the holder and theprobe as the drive mechanism moves the holder holding the probedownward; a movement mechanism having an arm to which a fitting jigfitted with the welding tool is fixed so as to be able to freely movethe welding tool with respect to the processing target member by movingthe arm; and a probe detection mechanism that can freely detect a tiplength, which is a length of a member of only the probe, as the drivemechanism moves the holder holding the probe downward, wherein thedetector can freely detect the amount of vertical movement of the holderand the probe held by the holder by the drive mechanism, and detects theamount of movement after the movement mechanism moves the arm so thatthe welding tool faces a mounting surface of the mounting member untilthe welding tool is moved down to press the mounting surface of themounting member by the tip of the probe.
 6. The friction stir weldingapparatus according to claim 5, further comprising a supplementarysupport mechanism that supports the mounting member by a support memberto supplementarily support only a vertical position of the processingtarget member, wherein at a time of detecting the amount of movementafter the movement mechanism moves the arm so that the welding toolfaces the mounting surface of the mounting member until the welding toolis moved down to press the mounting surface of the mounting member bythe tip of the probe, the welding tool is moved down to press themounting surface of the mounting member by the tip of the probe and thesupport member supports an opposite side to the mounting surface of themounting member.
 7. A friction stir welding apparatus comprising: amounting member on which a processing target member is mounted; awelding tool having a probe, a holder having a coefficient of thermalexpansion larger than that of the probe and holding the probedetachably, a drive mechanism that can drive the holder holding theprobe to freely move the probe vertically with respect to a processingtarget side surface of the processing target member and can freelyrotate with respect to the processing target member, and a detector thatcan freely detect a length of a member including the holder and theprobe as the drive mechanism moves the holder holding the probedownward; a movement mechanism having an arm to which a fitting jigfitted with the welding tool is fixed so as to be able to freely movethe welding tool with respect to the processing target member by movingthe arm; a probe detection mechanism that can freely detect a tiplength, which is a length of a member of only the probe, as the drivemechanism moves the holder holding the probe downward; a pressing memberthat can freely press the processing target member mounted on themounting member; and a processing-member detection mechanism having adisplacement sensor fixed to the mounting member side, wherein when thepressing member presses an upper surface of the processing targetmember, the contact member of the displacement sensor comes in contactwith the pressing member side and is moved, thereby detecting an amountof displacement of the contact member.
 8. The friction stir weldingapparatus according to claim 7, wherein the processing target member hasa lower member and an upper member, and when the pressing member pressesan upper surface of the lower member mounted on the mounting member, thecontact member of the displacement sensor comes in contact with thepressing member side and is moved, thereby detecting the amount ofdisplacement of the contact member, or when the pressing member pressesan upper surface of the upper member mounted on the lower member, thecontact member of the displacement sensor comes in contact with thepressing member side and is moved, thereby detecting the amount ofdisplacement of the contact member.
 9. The friction stir weldingapparatus according to claim 1, further comprising: a probe cleaningmechanism that cleans the probe; and a processing-member detectionmechanism having a displacement sensor fixed to the mounting memberside, wherein the probe cleaning mechanism has a roughing unit and afinal polishing unit, and at a time of cleaning the probe, after themovement mechanism moves the arm so that the welding tool faces theroughing unit, the welding tool is moved down to accommodate the tip ofthe probe in the roughing unit, and the welding tool is rotated to roughthe tip, and after the movement mechanism moves the arm so that thewelding tool faces the final polishing unit, the welding tool is moveddown to accommodate the tip of the probe in the final polishing unit,and the welding tool is rotated to polish the tip, and wherein the probedetection mechanism, the processing-member detection mechanism, theprobe cleaning mechanism, and the processing target member mounted onthe mounting member are arranged within a movable range of the weldingtool defined by the movement of the arm by the movement mechanism. 10.The friction stir welding apparatus according to claim 1, wherein themovement mechanism is an industrial robot.
 11. The friction stir weldingapparatus according to claim 5, further comprising: a probe cleaningmechanism that cleans the probe; and a processing-member detectionmechanism having a displacement sensor fixed to the mounting memberside, wherein the probe cleaning mechanism has a roughing unit and afinal polishing unit, and at a time of cleaning the probe, after themovement mechanism moves the arm so that the welding tool faces theroughing unit, the welding tool is moved down to accommodate the tip ofthe probe in the roughing unit, and the welding tool is rotated to roughthe tip, and after the movement mechanism moves the arm so that thewelding tool faces the final polishing unit, the welding tool is moveddown to accommodate the tip of the probe in the final polishing unit,and the welding tool is rotated to polish the tip, and wherein the probedetection mechanism, the processing-member detection mechanism, theprobe cleaning mechanism, and the processing target member mounted onthe mounting member are arranged within a movable range of the weldingtool defined by the movement of the arm by the movement mechanism. 12.The friction stir welding apparatus according to claim 5, wherein themovement mechanism is an industrial robot.
 13. The friction stir weldingapparatus according to claim 7, further comprising a probe cleaningmechanism that cleans the probe, wherein the probe cleaning mechanismhas a roughing unit and a final polishing unit, and at a time ofcleaning the probe, after the movement mechanism moves the arm so thatthe welding tool faces the roughing unit, the welding tool is moved downto accommodate the tip of the probe in the roughing unit, and thewelding tool is rotated to rough the tip, and after the movementmechanism moves the arm so that the welding tool faces the finalpolishing unit, the welding tool is moved down to accommodate the tip ofthe probe in the final polishing unit, and the welding tool is rotatedto polish the tip, and wherein the probe detection mechanism, theprocessing-member detection mechanism, the probe cleaning mechanism, andthe processing target member mounted on the mounting member are arrangedwithin a movable range of the welding tool defined by the movement ofthe arm by the movement mechanism.
 14. The friction stir weldingapparatus according to claim 7, wherein the movement mechanism is anindustrial robot.